1. Field of the Invention
The present invention relates to a toner cartridge for replenishing a development device with a toner material of a colorant for developing an electrostatic latent image into a visible image, the development device provided in an electrophotographic type image forming apparatus, such as copiers, printers and the like, for developing the electrostatic latent image formed on a recording medium into the visible image.
2. Description of the Related Art
The electrophotographic type image forming apparatuses such as copiers, printers and the like, are adapted to form an electrostatic latent image corresponding to an image to be reproduced on a surface of a photosensitive material as a recording medium. The image forming apparatus comprises a development device for developing the electrostatic latent image into the visible image. The development device is adapted to supply a developer such as toner material of a colorant to the photosensitive material and to make the toner material adhere to the photosensitive material.
More specifically, in the image forming apparatus, the surface of the photosensitive material is first uniformly electrically charged and then irradiated with a light image corresponding to an image to be reproduced thereby removing the electric charge of the surface of the photosensitive material in a region irradiated with the light image. As a result, the electrostatic latent image is formed in correspondence to the image to be reproduced. For developing the electrostatic latent image into the visible image, the development device makes the toner adhere to the surface of the photosensitive material. Thus, the toner stored in the development device is consumed little by little on each production of a printed image.
In order to maintain the quality of images produced by the image forming apparatus at a certain level, the development device needs to be replenished with toner so as to make up for the consumption. In addition, the image forming apparatus is designed to store a constant amount of toner material at all times. On this account, the development device includes a toner feeder which is responsive to a detection of shortage of the toner material contained in the development device for automatically feeding a toner material to the development device. This ensures that the constant amount of toner material is kept constant in the development device thereby constantly maintaining a consistent level of quality of the produced images.
The toner feeder is to be preliminarily supplied with a sufficient amount of toner material. However, the toner feeder runs out of the toner material contained therein on each production of several thousands to tens of thousands of images, requiring a replenishment of toner material. The replenishment of toner material is normally conducted by a person such as a user manipulating the image forming apparatus. In this connection, the toner feeder adopts a toner cartridge system so as to afford convenience to the user who replenishes the toner feeder with a toner material.
FIG. 9 shows a typical construction of the toner cartridge for use in the electrophotographic type image forming apparatuses such as copiers, printers and the like. A toner cartridge 100 of a container such as formed of a resin material is filled with a toner material 101. The toner cartridge 100 has a toner discharge port 103 for feeding the toner material 101 to a hopper 110 of a toner feeder 102 provided in the image forming apparatus. The toner discharge port 103 is usually sealed with a sealing member or the like for prevention of toner leakage and thus, an interior of the toner cartridge 100 is hermetically enclosed.
To replenish the development device with the toner material in the toner cartridge 100, a user first mounts the toner cartridge 100 to the toner feeder so that the toner discharge port 103 fits in an inlet port 104 of the toner feeder 102. Subsequently, the user removes the sealing member closing the toner discharge port 103. Thus, the toner discharge port 103 is opened to be communicated with the inlet port 104 so that the toner material in the toner cartridge 100 is fed to the hopper 110 of the toner feeder 102.
This process needs to be performed smoothly and must ensure that all the toner material 101 in the toner cartridge 100 is fed to the hopper 110 positively and quickly. In other words, the process is required to save as much effort paid by the user as possible and to reduce work needed for the toner replenishment thereby saving time spent by the user involved in operations associated with the image forming apparatus.
Unfortunately, however, the toner cartridge 100 is placed on a floor of a store place for storage as standing on its bottom plate 105 opposite to the toner discharge port 103. Accordingly, as the toner cartridge is left standing over an extended period of time, the gravity causes subsidence of the toner material 101 contained therein so that the aggregation thereof occurs due to forces between toner particles such as Van der Waals force, Coulomb force due to static electricity, liquid crosslinking force and the like. Therefore, it is generally required in the art to sufficiently loosen the aggregated toner material 101 contained in the toner cartridge 100 left standing over an extended period of time so as to efficiently feed such a toner material 101 to the hopper 110 of the toner feeder 102.
Where fine particles like toner particles form aggregation, the aggregation of the fine particles exhibits a behavior similar to that of a solid matter. Therefore, if the toner cartridge 100 containing the aggregated toner material is mounted to the hopper 110 of the toner feeder 102 and the sealing member thereof is removed, the toner material does not flow through the toner discharge port 103, thus failing to be supplied to the hopper 110. Particularly, the aggregated toner material blocks the toner discharge port 103 or the inlet port 104 thereby making it difficult to feed the toner material 100. If, in this state, the user removes the toner cartridge 110 from the hopper 110 mistakenly determining that the toner feeding has been completed, the blocking toner material will be scattered around and a large amount of toner material remaining in the toner cartridge 100 will be discharged out of the cartridge.
For this reason, it is important for the user to shake vertically and laterally the toner cartridge 100 having been left standing so as to adequately loosen the aggregated toner material before mounting the toner cartridge to the hopper 110 and removing the sealing member. However, since the shaking of the toner cartridge 100 varies in degrees from one user to another, the aggregated toner material may sometimes fail to be adequately loosened. In such cases, the toner particles may be scattered around or discharged out of the cartridge, resulting in contamination of hands or clothes of the user.
Furthermore, mere shaking of the toner cartridge cannot bring all the aggregated toner material back to a particle state and hence, a part of the aggregated toner material remains yet to be loosened. When such a toner material is supplied to the toner feeder 102, a great portion of the toner material is left in the toner cartridge 100, resulting in the aforementioned problems. That is, if the user mistakenly removes the toner cartridge 100 when all the toner material therein has not been transferred to the hopper 110 of the toner feeder 102 yet, the toner scattering may result.
Hence, need exists for loosening the toner material aggregated in the toner cartridge 100 due to gravity and the like before the toner material is fed to the toner feeder 102. Although the manufacturers suggest that users shake the toner cartridge 100 adequately so as to loosen the toner material therein, some of many and unspecified users may fail to give the toner cartridge an adequate shake for loosening the toner material, as described above. In the case that the shake for loosening the toner material is inadequate, when the toner cartridge 100 is mounted to the hopper 110 of the toner feeder and the sealing member is removed from the toner cartridge so to start feeding the toner material to the toner feeder, inadequately loosened toner material by shaking may result in cases where all the toner material in the toner cartridge is not transferred to the toner feeder 102 or where a long period of time is required for replenishing the toner feeder with the toner material.
In this connection, a toner feeder designed to efficiently loosen such an aggregation of toner material and to provide a positive and quick toner feeding is disclosed in Japanese Unexamined Utility Model Publication JP-A 1-164458 (1989). As shown in FIG. 9, this toner feeder comprises residual toner removing means 106 pivotally provided in the toner cartridge 100. The residual toner removing means 106 comprises a support member 107 having one end thereof fixed to the cartridge 100 and a weight 109 attached to the support member by way of a coupling member 108 shaped like a coil.
Shaking the toner cartridge 100 brings the residual toner removing means 109 into an oscillation by way of a resilient force of the coil spring which is mainly the coupling member 108. This causes the weight 109 to agitate the toner material 101 in the toner cartridge 100 thereby loosening the aggregated toner material. Thus is accomplished an easy and quick toner feeding from the toner cartridge 100 to the toner feeder 102.
As described above, the toner feeder discussed in Japanese Unexamined Utility Model Publication JP-A 1-164458 (1989) contains therein the coil spring as a resilient member and the weight for agitating and loosening the toner material in the toner cartridge. Thus is offered a solution to the problem where the toner feeding leaves a great portion of the toner material in the toner cartridge.
However, it is anticipated that when a greater oscillation than expected is applied to the toner cartridge, the residual toner removing means 106 may break through the sealing member closing the toner discharge port 103 of the toner cartridge 100. Furthermore, in a case where the toner particles enter the coil spring of the coupling member 108 to form an aggregation therein, a sufficient resilient characteristic of the coil spring cannot be obtained. Therefore, an adequate agitation of the toner material is not accomplished, thus leaving a part of the toner material aggregated. Since the coil spring is utilized for bringing the weight into oscillation, the toner particles are prone to form aggregation in space between adjacent turns of the coil spring, thus producing residual toner material.